feat(复习): 节点级 focusPath + findNode，回退 session 维度

- 移除 MindMapNode.sessionNum、filterBySession、getTaskSessions
- 新增 MindMapTreeTool.extractSubtree() 按路径提取子树作为对比基准
- 新增 findClosestNode/getPath/similarityScore 支持节点匹配
- 新增 POST /review/standard-mind-map/{taskNum}/find-node
- recallCompare 使用 focusPath 替代 sessionNum
- ReviewRecallRecordEntity.focusPath 替代 sessionNum
- Flyway V20260706_1: review_recall_records 加 focus_path 列

src/main/java/com/guo/learningprogresstracker/service/impl/StandardMindMapServiceImpl.java

@@ -152,7 +152,7 @@ public class StandardMindMapServiceImpl implements StandardMindMapService {
 
     @Override
     @Transactional
-    public ReviewStandardMindMapEntity recallCompare(String taskNum, String recallOutline, String sessionNum)
+    public ReviewStandardMindMapEntity recallCompare(String taskNum, String recallOutline, String focusPath)
             throws NotFindEntitiesException, OperationFailedException {
         ensureTaskExists(taskNum);
 
@@ -163,9 +163,14 @@ public class StandardMindMapServiceImpl implements StandardMindMapService {
         MindMapNode standardRoot = MindMapTreeTool.fromJson(standard.getContent(), objectMapper);
         MindMapNode recallRoot = MindMapTreeTool.parseOutline(recallOutline);
 
-        // 2b. 若指定了会话维度，过滤标准导图只保留该会话相关节点
-        if (sessionNum != null && !sessionNum.isBlank()) {
-            standardRoot = MindMapTreeTool.filterBySession(standardRoot, sessionNum);
+        // 2b. 若指定了起点节点路径，提取该子树作为对比基准
+        MindMapNode compareRoot = standardRoot;
+        if (focusPath != null && !focusPath.isBlank()) {
+            compareRoot = MindMapTreeTool.extractSubtree(standardRoot, focusPath);
+            if (compareRoot == null) {
+                log.warn("focusPath 未匹配到节点，使用全量标准导图: path={}", focusPath);
+                compareRoot = standardRoot;
+            }
         }
 
         // 3. 执行对比（优先 AI 语义对比，失败时降级为内置算法）
@@ -176,19 +181,19 @@ public class StandardMindMapServiceImpl implements StandardMindMapService {
                     .getTaskName();
             var optJson = aiServiceClient.compareRecall(
                     taskName,
-                    MindMapTreeTool.toFullOutline(standardRoot),
+                    MindMapTreeTool.toFullOutline(compareRoot),
                     recallOutline
             );
             if (optJson.isPresent()) {
-                result = buildCompareResultFromAI(optJson.get(), standardRoot);
+                result = buildCompareResultFromAI(optJson.get(), compareRoot);
                 log.info("AI 回忆对比: taskNum={}, recallRatio={}, evaluation={}",
                         taskNum, result.getRecallRatio(),
                         result.getEvaluation() != null ? result.getEvaluation().substring(0, Math.min(50, result.getEvaluation().length())) : "");
             } else {
-                result = compareTrees(standardRoot, recallRoot);
+                result = compareTrees(compareRoot, recallRoot);
             }
         } else {
-            result = compareTrees(standardRoot, recallRoot);
+            result = compareTrees(compareRoot, recallRoot);
         }
 
         // 4. 序列化对比结果
@@ -203,7 +208,7 @@ public class StandardMindMapServiceImpl implements StandardMindMapService {
         ReviewRecallRecordEntity record = new ReviewRecallRecordEntity();
         record.setTaskNum(taskNum);
         record.setStandardMapId(standard.getId());
-        record.setSessionNum(sessionNum != null && !sessionNum.isBlank() ? sessionNum : null);
+        record.setFocusPath(focusPath != null && !focusPath.isBlank() ? focusPath : null);
         record.setRecallContent(recallOutline);
         record.setCompareResult(resultJson);
         record.setRecallRatio(result.getRecallRatio());
@@ -219,6 +224,29 @@ public class StandardMindMapServiceImpl implements StandardMindMapService {
         return standard;
     }
 
+    // ============ 节点查找 ============
+
+    @Override
+    public Map<String, Object> findNode(String taskNum, String content) throws NotFindEntitiesException, OperationFailedException {
+        ensureTaskExists(taskNum);
+        ReviewStandardMindMapEntity standard = getOrGenerate(taskNum);
+        MindMapNode root = MindMapTreeTool.fromJson(standard.getContent(), objectMapper);
+
+        MindMapNode closest = MindMapTreeTool.findClosestNode(root, content);
+        Map<String, Object> result = new LinkedHashMap<>();
+        if (closest != null) {
+            String path = MindMapTreeTool.getPath(root, closest.getTitle());
+            result.put("path", path);
+            result.put("nodeTitle", closest.getTitle());
+            result.put("score", MindMapTreeTool.similarityScore(closest.getTitle(), content));
+        } else {
+            result.put("path", "");
+            result.put("nodeTitle", "");
+            result.put("score", 0.0);
+        }
+        return result;
+    }
+
     // ============ 对比算法核心 ============
 
     /**